Composite structures have an advantageous combination of high strength and lightweight. As such, composite structures commonly find use in aerospace and other industries where such properties are beneficial. For example, the surface skins of modern aircraft may commonly be formed of composite structures.
Composite structures include reinforcing fibers impregnated with a resin matrix. Often, it may be necessary to attach the composite structure to another structure, such as a second composite structure or an internal structural support (e.g., a stiffener). The strength of the bond between composite structures may depend on the surface characteristics of the composite structure.
Commonly, the surface of the composite structure may be relatively smooth and exhibit relatively weak bonding strength and durability. As a result, methods have been developed to increase the bonding strength and durability of the surface of the composite structure. One such method is the use of a peel ply during the manufacture of a composite structure. A peel ply typically includes a sheet of dry woven fabric or a sheet of woven fabric impregnated with a resin matrix. The peel ply may be placed on an uncured surface of the composite structure. The composite structure and the peel ply are then co-cured. Once cured, the peel ply may be removed from the surface of the composite structure. Once the peel ply is removed, the surface of the composite structure may be roughened or textured.
Removal of the peel ply is intended to generate a clean surface ready for bonding. A supplementary ablation surface treatment after removal of the peel ply, such as abrasion or plasma, may be required to ensure removal of any peel ply residue that could impact bonding performance. Inspection of the pre-bond surface to verify complete removal of any residue transferred to the surface may also be required and can be expensive and/or time consuming.
Accordingly, those skilled in the art continue with research and development efforts in the field of preparing a surface of a composite structure for bonding and pre-bond surface inspection.